Abstract
<p>Previous, research focused mainly on the effects of conservation agriculture (CA) and conventional practices (CP) on crop yield mostly. A study was conducted at five sites in Zimbabwe from 2012 to 2014 to investigate effects of CA and CP practices on emergence, chlorophyll content, early vigour and grain yield of different maize varieties using 12 hybrids and 4 open pollinated varieties (OPVs). The experiment was laid as a 4 × 4 alpha lattice design with three replications. Emergence was higher under CA (75%) at University of Zimbabwe (UZ) in 2012/13 and Domboshawa Training Centre (DTC) (67%) compared to CP (71% and 39% respectively). Lower early plant vigour was observed under CA compared to CP at most sites. CA had lower leaf chlorophyll content during the early crop growth stages compared to CP. However, at some instances, CA had higher leaf chlorophyll content (45 units) than CP (35 units) at 78 days after sowing in Zimuto 2012/13. For maize yield, CA outperformed CP on a sandy loamy soil (3050 kg ha<sup>-1</sup> vs 2656 kg ha<sup>-1</sup>) and clay soil (4937 kg ha<sup>-1</sup> vs 4274 kg ha<sup>-1</sup>). However, on a sandy soil, CP outperformed CA (1764 vs 1313 kg ha<sup>-1</sup>). Our results suggest that tillage effects on early maize plant vigor, leaf chlorophyll content and the final yield can be site and season specific. Furthermore, a delay of nutrient release for plant uptake under CA systems was found and potentially implies investigations of new fertilization strategies for such cropping systems.</p>
Highlights
Agriculture systems based on tillage and removal/or burning of crop residues pose a threat to food security through accelerated soil degradation (Thierfelder, Mutenje, Mujeyi, & Mupangwa, 2014)
The performance of maize varieties was tested on different soil types and rainfall regimes under two cropping systems (CA and cultivation practices (CP)) at five locations of Zimbabwe
Chlorophyll content and early vigour characteristics were different under the two cropping systems which indicate the need to select maize varieties that are nutrient-efficient and suitable under Conservation agriculture (CA) systems
Summary
Agriculture systems based on tillage and removal/or burning of crop residues pose a threat to food security through accelerated soil degradation (Thierfelder, Mutenje, Mujeyi, & Mupangwa, 2014). Compared with conventional plough- or hoe-based cultivation practices (CP), CA practices have been shown to increase and stabilize maize yields in studies conducted in different parts of the world (Govaerts, 2009; Thierfelder et al, 2014; Mhlanga, Cheesman, Maasdorp, Mupangwa, & Thierfelder, 2015) This increase in crop yields under CA could be attributed to increased soil moisture induced by residue retention, increased faunal abundance achieved by reduced disturbance of the soil and residue retention, and increased nitrogen (N) fixation from crop rotations with legumes (Mhlanga et al, 2015; Mutema, Mafongoya, Nyagumbo, & Chikukura, 2013; Thierfelder & Wall, 2009). The smallholder farmers still regard CP as an easier farming method based on how weeds are controlled at the beginning of the season through ploughing which buries the weeds jas.ccsenet.org
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